A Mg (magnesium) base alloy is currently known as a lightweight material used for a housing or the like of a portable terminal. However, there is such a disadvantage that the Mg base alloy is low in corrosion resistance. Thus, it is studied that a clad material in which a layer made of the Mg base alloy and a layer made of an Al (aluminum) base alloy are bonded to each other is prepared such that a material in which an Al base alloy enables improvement in corrosion resistance while a Mg base alloy enables weight saving is obtained.
However, when the clad material is prepared by directly bonding the layer made of the Mg base alloy and the layer made of the Al base alloy to each other, a fragile intermetallic compound is deposited on a bonding interface between the layers, and hence there is such a disadvantage that the layers are likely to be separated from each other.
In order to suppress the separation of the layers, a clad material in which a layer made of a Mg base alloy and a layer made of an Al base alloy are bonded to each other through a layer made of Cu is known in general. Such a clad material is disclosed in International Patent Application Publication 2011/155214, for example.
International Patent Application Publication 2011/155214 discloses a combined member including a magnesium member made of an alloy that mainly contains Mg, an aluminum member made of an alloy that mainly contains Al, and an intermediate layer arranged between the magnesium member and the aluminum member and made of Cu. International Patent Application Publication 2011/155214 also discloses a combined member in which a magnesium alloy billet made of AZ80 that contains 8 mass % of Al, less than 1 mass % of Zn, the balance Mg, and inevitable impurity elements, an insert material made of Cu, and an aluminum alloy billet made of A6151 are bonded to each other as an example.